1. Field of the Invention
The present invention relates to a process for producing a halogenated benzene derivative by halogenating benzene and/or a benzene derivative in the liquid phase. More particularly, the present invention relates to a process for selectively producing a p-substituted halobenzene derivative by halogenating benzene and/or a benzene derivative in the liquid phase using, as a catalyst, a faujasite type zeolite in the presence of any one member selected from the group consisting of sulfur-containing compounds, nitrogen-containing organic basic compounds, salts of said nitrogen-containing organic basic compounds, and a mixture of said nitrogen-containing organic basic compounds and salts thereof.
2. Description of the Prior Art
Halogenated benzene derivatives are important raw materials or intermediates in various fields such as medicines, agricultural chemicals and organic synthesis chemistry. They are ordinarily produced by halogenating benzene and/or a benzene derivative in the liquid phase using, as a catalyst, a Lewis acid such as ferric chloride, antimony chloride or the like. For instance, dichlorobenzene (hereinafter abbreviated to DCB) is produced by blowing chlorine gas into benzene or monochlorobenzene (hereinafter abbreviated to MCB) in the presence of ferric chloride.
As is well known, in the production of a di-substituted benzene derivative by the liquid phase halogenation of a mono-substituted benzene derivative, three isomers, namely, a 1,2-di-substituted benzene derivative (an o-isomer), a 1,3-di-substituted benzene derivative (an m-isomer) and a 1,4-di-substituted benzene derivative (a p-isomer) are formed as products. The proportions of these isomers are decided by the kind of existing substituent on the mono-substituted benzene derivative, the kind of catalyst used, etc. For instance, in the production of DCB by liquid phase chlorination of MCB in the presence of ferric chloride, the following three isomers are formed in the following proportions.
______________________________________ o-Dichlorobenzene 30 to 40% m-Dichlorobenzene 0 to 5% p-Dichlorobenzene 60 to 70% ______________________________________
In the three isomers of di-substituted halobenzene derivatives, p-substituted halobenzene derivatives are in the greatest demand and are most important industrially. Hence, a number of processes have hitherto been proposed for the selective production of p-substituted halobenzene derivatives.
These prior arts include processes for selectively producing a p-substituted halobenzene derivative by halogenating benzene and/or a benzene derivative using a zeolite as a catalyst in place of a Lewis acid. For instance, "Journal of Catalysis"60, 110 (1979) describes the use of zeolite as a catalyst for bromination of a halogenated benzene. In this literature, it is indicated that a p-substituted bromobenzene derivative can be produced selectively by using, as a bromination catalyst, various ion-exchanged X type and Y type zeolites.
Further, "Tetrahedron Letters" 21, 3809 (1980) describes the chlorination of benzene using various catalysts such as ZSM-5, ZSM-11, mordenite, L type zeolite and Y type zeolite. It is indicated in this literature that L type zeolite, in particular, can produce p-dichlorobenzene (hereinafter abbreviated to PDCB) at a high selectivity. Furthermore, Japanese Patent Public Disclosure (Laid-Open Publication) Nos. 130227/1984, 144722/1984 and 163329/1984, for example, disclose processes for halogenating benzene or an alkylbenzene using L type zeolite or Y type zeolite as a catalyst.
It is known that, the selectivity of a p-substituted halobenzene derivatives is improved, if one of the various sulfur-containing compounds is added as a cocatalyst into the reaction system, where a Lewis acid such as ferric chloride is used as a catalyst. For instance, U.S. Pat. No. 3,226,447 states that in chlorination of benzene, MCB or the like, a p-substituted halobenzene derivative can be produced at a higher selectivity by adding an organic sulfur compound containing divalent sulfur to a Lewis acid catalyst (e.g., ferric chloride). More specifically, it is indicated in this cited literature that, if chlorination of benzene is effected using iron and thioglycollic acid as catalysts, the proportion of PDCB in the produced DCB reaches 77%. In addition, U.S. Pat. No. 1,946,040 and British Pat. No. 1,153,746, for example, disclose processes for producing a p-substituted halobenzene derivative using sulfur or an organic sulfur compound as a catalyst, together with a Lewis acid catalyst such as ferric chloride, antimony trichloride or the like, in chlorination of an alkylbenzene or the like. Further, it is described in Chemistry Letters, pp. 2007-2008, (1984) that in bromination of aniline using A type zeolite having bromine adsorbed thereon, addition of pyridine or 2,6-lutidine improves brominating activity and the selectivity of para-bromoaniline.
However, it is known to those skilled in the art that a Lewis acid catalyst is essential for the above-described known processes.
It is obvious from the prior arts that in halogenation of benzene and/or a benzene derivative, processes using a zeolite catalyst can produce a p-substituted halobenzene derivative at a higher selectivity than conventional processes using a Lewis acid catalyst (e.g., ferric chloride).
However, the selectivity of a p-substituted halobenzene derivative in the said prior art processes which use a zeolite catalyst is still insufficient from the industrial viewpoint. Accordingly, it is desired to develop a process for producing a p-substituted halobenzene derivative at an enhanced selectivity.
In view of the above-described circumstances, the present inventors examined in detail the processes for selectively producing a p-substituted halobenzene derivative by liquid phase halogenation of benzene and/or a benzene derivative, and particularly, directed their attention to halogenation reactions which use a zeolite as a catalysts.
As a result, the present inventors found that, if halogenation of benzene and/or a benzene derivative is carried out using a faujasite type zeolite as a catalyst in the presecce of any one member selected from the group consisting of sulfur-containing compounds, nitrogen-containing organic basic compounds, salts of said nitrogen containing organic basic compounds and a mixture of said nitrogen-containing organic basic compounds and salts thereof, the ratio of produced di-substituted isomers surprisingly enough changes with no substantial lowering of activities, and the selectivity of a p-substituted halobenzene derivative is enhanced.
As described above, it is known that, when a Lewis acid such as ferric chloride is used as a catalyst in halogenation of benzene and/or a benzene derivative, addition of a sulfur-containing compound as a cocatalyst enhances the selectivity of a p-substituted halobenzene derivative. It is considered that such advantageous effect is made available by the fact that the Lewis acid is modified by the sulfur-containing compound. More specifically, in the liquid phase halogenation using a Lewis acid catalyst, the Lewis acid is dissolved in a reaction mixture to perform a catalytic reaction in a homogeneous system, and therefore it is estimated that a sulfur-containing compound, which is similarly dissolved in the reaction mixture changes the properties of the Lewis acid by, for example, coordination.
On the other hand, in the liquid phase halogenation using a zeolite catalyst, the zeolite is not dissolved in the reaction mixture, and acts as a heterogeneous catalyst. Therefore, the working mechanism of the zeolite catalyst is completely different from that of a Lewis acid catalyst. Further, the advantageous effect which is offered by a zeolite catalyst in the presence of a sulfur-containing compound is particularly unique to faujasite type zeolites. Accordingly, the effect obtained by the presence of a sulfur-containing compound is completely different from the cocatalytic effect thereof in the case of a reaction using a Lewis acid catalyst. Thus, the present invention has been accomplished on the basis of the finding of this new fact. In addition, it is known, as described above, that in bromination of aniline using A type zeolite having bromine adsorbed thereon, addition of pyridine or 2,6-lutidine enables both brominating activity and the selectively of para-bromoaniline to be enhanced. However, there is no suggestion in the cited literature that a compound such as pyridine is effective in improving liquid phase halogenation of benzene and/or a benzene derivative using a faujasite type zeolite.